NAVLE Canine and Feline: High-Yield Topics Every Student Must Know

Canine and feline questions together represent approximately 35–45% of the NAVLE — the largest combined species bloc. Most students feel most comfortable in these categories, which creates a false sense of preparedness. The NAVLE tests canine and feline content at significant depth, including subtle disease distinctions, drug differences between species, and complex multi-system conditions. This guide covers the highest-yield content in both species.

Why You Still Need to Study Canine and Feline

The comfort trap: students who have done extensive canine and feline clinical work assume they know these sections and over-invest in studying other species. This works until the exam reveals gaps in specific high-yield areas — endocrinology, oncology, or infectious disease — that clinical rotations do not always cover in detail. Canine and feline are comfortable but not easy. They require deliberate preparation, not just reliance on clinical intuition.

Canine — High-Yield Topics

Endocrine Disease

• Diabetes mellitus: Type 1 (insulin-dependent) predominates in dogs. Signs: PU/PD, polyphagia, weight loss, cataracts (dogs develop diabetic cataracts — cats do not). Diagnosis: persistent fasting hyperglycemia + glucosuria. Treatment: NPH or lente insulin in dogs, diet, exercise regulation.
• Hypothyroidism: Most common endocrine disease in dogs. Clinical signs: weight gain, lethargy, bilaterally symmetric alopecia, cold intolerance, hypercholesterolemia. Diagnosis: low total T4 ? confirm with free T4 by equilibrium dialysis + TSH if equivocal. Treatment: levothyroxine.
• Hyperadrenocorticism (Cushing's disease): PDH (pituitary-dependent) most common (~85%) vs adrenal tumor (~15%). Signs: PU/PD, pot-bellied appearance, alopecia, muscle weakness, panting, thin skin. Diagnosis: LDDST, urine cortisol:creatinine ratio for screening; HDDST or abdominal ultrasound to differentiate PDH vs AT. Treatment: trilostane (preferred), mitotane. Monitoring: ACTH stimulation test.
• Hypoadrenocorticism (Addison's disease): Primary = glucocorticoid + mineralocorticoid deficiency. Signs: waxing/waning GI signs, weakness, collapse. Classic: "Addisonian crisis" — hyponatremia, hyperkalemia, bradycardia, hypotension. Na:K ratio <27 is suspicious. Treatment: acute crisis (IV fluids, dexamethasone), chronic (fludrocortisone or DOCP + prednisone).

Oncology

• Mast cell tumor (MCT): Most common skin tumor in dogs. Varies from benign to aggressive. Grading: Patnaik (I–III) or Kiupel (low-grade, high-grade). Darier's sign (reddening on pressure). Treatment: surgical excision with wide margins + adjuvant chemotherapy (prednisone, vinblastine) for high-grade. Antihistamines preoperatively.
• Lymphoma: Most common hematopoietic malignancy. Multicentric most common (peripheral lymphadenopathy). Alimentary, mediastinal forms also occur. Diagnosis: cytology or biopsy. Treatment: CHOP protocol (cyclophosphamide, doxorubicin, vincristine, prednisone). Median survival 12–14 months with treatment.
• Osteosarcoma: Appendicular most common — large and giant breeds. Distal radius, proximal humerus most common sites. Marked periosteal reaction on radiographs ("sunburst pattern," Codman's triangle). Amputation + chemotherapy (carboplatin or doxorubicin). Median survival 10–12 months with treatment.
• Hemangiosarcoma: Splenic most common location in dogs. German Shepherds predisposed. Hemoabdomen — sudden collapse, pale mucous membranes, rapid decompensation. Emergency splenectomy. Poor prognosis even with surgery + chemotherapy.

Cardiology

• Myxomatous mitral valve disease (MMVD): Most common heart disease in dogs. Cavalier King Charles Spaniels predisposed. Progressive regurgitation ? left atrial enlargement ? pulmonary edema. Treatment: pimobendan + furosemide + ACE inhibitor (enalapril/benazepril) when CHF develops.
• Dilated cardiomyopathy (DCM): Large breed dogs (Doberman, Great Dane, Boxer). Eccentric hypertrophy ? systolic dysfunction. Dobermans: high risk of ventricular arrhythmias and sudden death. Treatment: pimobendan, digoxin for rate control, furosemide, antiarrhythmics. Grain-free diet-associated DCM — FDA investigation ongoing.
• Pericardial effusion: Muffled heart sounds, distended jugular veins, pulsus paradoxus. Echocardiography diagnostic. Pericardiocentesis therapeutic. Causes: hemangiosarcoma (right atrium), mesothelioma, idiopathic.

Canine Infectious Disease

• Parvovirus: Young, unvaccinated dogs. Bloody diarrhea, vomiting, leukopenia. Treatment: supportive (IV fluids, antiemetics, antibiotics, parvogard/oseltamivir controversial).
• Distemper: Multisystemic — respiratory, GI, neurological. Old dog encephalitis form. Distemper is a paramyxovirus. Hardpad (hyperkeratosis of footpads). No specific treatment — supportive care.
• Leptospirosis: Zoonotic — Leptospira serovars. Acute renal failure, hepatopathy, coagulopathy, uveitis. Diagnosis: MAT, PCR. Treatment: doxycycline (initial), then amoxicillin (renal clearance phase). Vaccine: 4-serovar available.
• Tick-borne disease: Ehrlichia canis (monocytic ehrlichiosis — thrombocytopenia, bleeding), Anaplasma phagocytophilum (granulocytic anaplasmosis), RMSF (Rickettsia rickettsii — most severe; dermatitis, thrombocytopenia, coagulopathy). Treatment: doxycycline for all.

Feline — High-Yield Topics

Key Differences From Dogs — The Most Tested Area

The NAVLE frequently tests species differences between dogs and cats. These differences are high-yield because they are testable and clinically significant: